1 foot is 12 inches, so 2 feet are 24 inches.
The ratio is therefore 24/52. However, you're asked to have the lowest terms fraction, so let's look at common factors:
24 = 2*2*2*3
52 = 2*2*13.
The two numbers share a common factor of 4, so divide by 4 on both sides of the equation for success:
24/52 = 6/13.